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For specialist bone screws and smaller implants, it is very important to simulate machining beforehand

Medical Machining Challenges in the healthcare industry

Dec 1, 2015

Healthcare companies are under pressure to provide this higher quality at lower cost and to increase their productivity to meet the growing demand. In order to meet these requirements, it is important to use advanced CAD/CAM software and CNC machines for machining of medical devices.

As per a recent market report, India imports nearly 75% of all medical devices. The medical devices market in India, according to a leading analyst company, is over 3 billion US dollars annually, currently. This number will grow higher in the coming years. The reason for such massive imports is largely due to archaic standards, very little or no encouragement for indigenisation and improper application of said devices – to name a few. Adding to this, the comparative availability of trained professionals in the medical device domain – particularly in machining, to that of other engineering or medical fields adds to the challenges faced by the healthcare industry in our country. About 20% of these imported devices are made through direct high-end manufacturing / machining processes. This in itself is close to over 600 million US dollars a year.

Driving factors

Companies in the healthcare industry face the same demands from their patients that traditional engineering clients see from their customers for faster delivery of better and cheaper products. Patients want to receive higher quality products and services, and they want to complete their treatment in the shortest-possible time. At the same time, healthcare companies are under pressure to provide this higher quality at lower cost and to increase their productivity to meet the growing demand. These requirements can only be met through the application of more advanced and more automated technology. Multi-tasking machines are being used increasingly in the medical and dental industries, applications include the manufacture of all types of medical and dental screw, prosthetics, and components for medical equipment.

In order to drive these complex and multi-tasking machines, it is always important to use a CAM software that complements these machines in every way. The primary reason for using advanced CAD/CAM software and CNC machines, is to reduce the overall time and cost for creating the medical component. The benefits of medical machining may offer opportunities for reduced waiting times for the patient, avoiding unnecessary surgery, compress process times, reduce patient trauma, speed up patient recovery time and finally reduce medical costs – both for individuals and insurance companies.

Design & manufacture

For example, Delcam’s healthcare solutions help design and manufacture custom-made maxillofacial implants for patients suffering with tumours or major bone loss. Typically, the reconstructive surgery carried out at the time involved a bone graft using a shaped portion of patient’s fibula. Aesthetic outcomes were often poor and the patient had to endure a lengthy period in a leg plaster cast while the fibula healed. Ideally, the surgeons would like to operate well beyond the margins of the tumour and insert the custom-made implant in the same procedure. Therefore, surgeons want implants to be ready in time for the surgery and also that these implants are accurate in every aspect.

The process used by customer begins when patient data in either a CT or MRI scan is received. This data is converted into STL format to produce prototype models of the skull and the implant. This enables the operation procedure to be practised in advance and ensures that there are no surprises in the operating theatre. The same technology is also used to produce drilling jigs and/or cutting jigs needed by the surgeon. The next decision concerns the manufacturing method for the implant. The more straightforward examples can be machined directly from medical-grade titanium using five-axis machining; but the more complex implants require a combination of additive manufacturing and machining.

As far as bone screws and smaller dental implants are concerned, these are manufactured using a special type of machine called a Swiss-lathe. The Swiss-lathe is a multi-tasking machine that performs multiple operations simultaneously. Typically, the medical parts machined on Swiss-lathe are less than 25 mm in diameter. One can only imagine how critical and complicated it is to sequence the many moving parts and axes of a Swiss-type machine. Using a patented approach called divide-and-conquer, the programmer is able to view the part the same way the multi-axis lathe on which it is being machined sees it. The software does so by breaking down a part into a series of machining tasks for different part faces programmed in ‘Face Windows.’ It lets the user see a multi-axis turn-mill for what it really is, which is to say, not just a mill and a lathe, but really a lathe with up to nine different types of milling capabilities, depending on the capabilities of the machine and the engineering requirements of the part at hand. Thus, this approach lets a user quickly program a part in the exact way his machine will cut the component.

For specialist bone screws and smaller implants, it is very important to simulate machining beforehand. Often their critical features are not visible to the naked eye. However, the machines and tooling used to make these parts are huge by comparison. With a computer-generated simulation of the machining process, the user can see in exacting detail what the part will look like after it’s been programmed, no matter how small it is. In addition, with a full simulation of the machine tool itself, the user can see what, if any, machine collisions might occur during the manufacturing of a part.

Education & training

Although these technologies are available and can be employed on a full scale, they do require skilled manufacturing engineers to be employed in order to achieve the desired results. For example, machining expertise in an aerospace company – where he worked earlier, helped a Delcam customer in optimising medical machining. Many of the materials used in medical machining are aerospace grades of aluminium and titanium that the engineer was familiar with from his earlier career and helped him reduce the machining time by half in a particularly important project.

It may not always be possible to invest in skilled manufacturing workforce. There are tools like the Delcam Custom Software Core, which is a library of middleware software that allows one to interface their .NET applications to PowerMILL (CAM) and PowerSHAPE (CAD) software. This allows development professionals to streamline processes in a user-friendly and intuitive way, so that many complex tasks of medical device designs and CNC programming are greatly simplified.

The custom solution, for example, can be used to automate the following -

  • CAD process (iterative design)

  • Toolpath calculation

  • Post-processing

  • NC program transfer to the CNC

  • Computer aided inspection process

  • Report generation

  • Archiving and retrieval

3D printing

An area of emerging interest is 3D printing, which essentially means that a component is built layer by layer, literally. A subset of additive manufacturing, 3D printing helps save material wastage as the raw material is typically in powder form, fused by a variety of techniques – usually depending on the material and the 3D printing machine, to form the 3D part, which is input as a triangulated mesh CAD model. While 3D printing allows for complex shapes to be created that is otherwise not possible with subtractive machining, it is a much slower process and often quite expensive. Having said this, the cost of 3D printers are now coming down and there are also more material that are available for 3D printing.

3D printing is not limited to metal implants and generic medical devices alone. Even in the field of mass customisation, by combining the functionality of different software modules, Delcam has been able to generate and print a series of concept designs which demonstrate some of the possibilities for devices such as custom foot orthotics to be created by 3D printing. The process comprised of creating the orthotic designs where additional product features were added. These included structural ribs for strength, high resolution 3D relief for aesthetics and textures/aeration holes for potential clinical benefits.

Additive manufactured custom orthotic insoles process does not replace the faster and more economical subtractive milling method but it does open some new and interesting doors. For example, by 3D printing an orthotic, the practitioner is able to design the ideal custom insole unhindered by the restrictions of conventional manufacturing. For the immediate and present future, it is best to combine the strengths of additive and subtractive manufacturing – where possible, to derive the best value out of the process.

With all of the above developments, manufacturers now have the opportunity to cater to any form of medical device or equipment manufacture without the need to change or switch between different CAD/CAM providers. This in itself will reduce half the complexities.

Image Gallery

  • For specialist bone screws and smaller implants, it is very important to simulate machining beforehand

  • With a computer-generated simulation of the machining process, the user can see in exacting detail what the part will look like after it’s been programmed, no matter how small it is

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